The present disclosure relates to memory devices, and more particularly, to non-volatile memory devices.
A non-volatile memory device (e.g., a flash memory device) may use an erase-before-write operation. For example, if a write operation on a sector (e.g., 512 Bytes) of a flash memory device is requested, the write operation may be carried out after a block including the write-requested sector is erased. In contrast with a hard disk that supports a sector overwrite operation, input/output operations of the flash memory device may be relatively slow. Furthermore, a memory block of a flash memory device may become an unusable block after it experiences erase operations a relatively large number of times (e.g., over 100,000 times). Attempts have thus been made to prevent erase operations from focusing on a specific block of a flash memory device.
For example, a Flash Translation Layer (FTL) may include software that attempts to manage a flash memory device more efficiently. The FTL may receive a Logical Sector Number (LSN) from a file system and convert the LSN into a Physical Sector Number (PSN), which may be an address to be used at the flash memory device. The FTL may use an address map table for the conversion from the LSN to the PSN. The address map table may be stored in a Random Access Memory (RAM). The address map table may store information indicating a correlation between a logical address and a physical address.
Address mapping methods may include a page mapping method, a block mapping method, and a hybrid mapping method. A page mapping method may include forming a map table by the page converting a logical page into a physical page. A block mapping method may include performing a mapping operation by the block. A hybrid mapping method may use a combination of a page mapping method and a block mapping method.
A memory block may include dozens or hundreds of pages. If a page mapping method is used, a size of a map table may increase as compared with using a block mapping method. In other words, the page mapping method may require a relatively large memory space to manage a map table. If memory space is scarce/deficient, then mapping information may be loaded onto a map table from a meta area of a flash memory device, which may decrease the read performance of the flash memory device.